A storage device is a device storing data under the control of a host device such as a computer, a smart phone, a smart pad, etc. A storage device may include a device storing data in a magnetic disk such as a HDD (hard disk drive) or a device storing data in a semiconductor memory, in particular, a nonvolatile memory such as an SSD (solid state drive), a memory card, etc.
Examples of a nonvolatile memory include a ROM (read only memory), a PROM (programmable ROM), an EPROM (electrically programmable ROM), an EEPROM (electrically erasable and programmable ROM), a flash memory, a PRAM (phase-change RAM), an MRAM (magnetic RAM), an RRAM (resistive RAM), a FRAM (ferroelectric RAM), etc.
As semiconductor manufacturing technology develops, high integration and a higher capacity of a nonvolatile memory or a storage device are continuously proceeding. A high integration of a nonvolatile memory or a storage device has an advantage of reducing its production cost. However, as a scale of a nonvolatile memory or a storage device is reduced and its structure is changed due to the high integration of the nonvolatile memory of the storage device, various problems that were not previously known are being found. The various problems being newly found may damage data stored in the nonvolatile memory or the storage device and thereby reliability of the nonvolatile memory or the storage device may be degraded. A requirement for a method and a device that can improve reliability of the nonvolatile memory or the storage device is continuously being suggested.